Progress in Cu-based electrocatalysts for electrochemical CO2 reduction to C2+ products

Electrochemical carbon dioxide reduction reaction (CO2RR) into multi-carbon (C2+) products with higher energy density and wider applicability is a promising route for CO2 utilization. However, the selectivity and yield of C2+ products remain challenging owing to the involvement of multiple electron transfer and the competing reaction, i.e., the hydrogen evolution reaction (HER). Here, we review recent progress in Cu-based electrocatalysts for CO2RR to C2+ products. First, possible reaction pathways for CO2RR to C2+ products are discussed, focusing on the mechanism of C-C bond formation. Then, strategies of Cu-based electrocatalysts for CO2RR into C2+ products are summarized, the key of which is the modulation in C-C coupling of intermediates, leading to different product selectivities. In addition, the progress in in situ techniques for the elucidation of the mechanism is underlined, which is conducive to the precise design of efficient electrocatalysts. The outlooks along with current challenges are finally proposed for the future development of C2+-oriented CO2RR systems.